Gate valves have been used for many years to control the flow of solid particles or pieces through elongated conduits which have lateral openings through which material is permitted to flow from time to time down through a hopper, which converges to a throat where a conventional gate valve regulates flow of material through the hopper. In a typical installation, a rotatable auger screw moves product through the elongated conduit, which is often an upwardly opening U-shaped trough with lateral discharge openings spaced longitudinally so material can be dropped into hoppers at different locations. A separate gate valve in the hopper at each lateral discharge opening is opened and closed from time to time to achieve desired distribution of the product. Some solid materials tend to form clumps, especially during the period when the gate valve is closed, which obstruct the flow of material down through the hopper when the gate is subsequently opened. Those troublesome materials include fruit products, such as grapes, and cohesive powdered materials, such as cement, fertilizer, and the like.
The gate valves used in the past to control the flow of materials suffer from the following disadvantages:
1. They are expensive, and are difficult to maintain and repair; PA1 2. They are mounted in a way that promotes clumping of material, and prevents visual inspection to ensure satisfactory operation; and PA1 3. They require disassembly when blockage occurs, causing expensive, time-consuming interruption of production.